1. Field of the Invention
The present invention relates to a method of evaluating the performance of organic samples, such as ion-exchange film. The invention also relates to an X-ray measuring apparatus that is fit for use in this method.
2. Description of the Related Art
Recently, various apparatuses including macromolecular organic materials are provided in the industry. In the field of fuel cells, for example, the main component of the fuel cell is ion-exchange film that is made of macromolecular organic material. As FIG. 11 shows, the fuel cell comprises a pair of electrodes, or fuel pole 51 and air pole 52, and an ion-exchange film 29 interposed between the poles 51 and 52. Hydrogen (H2), i.e., the fuel, is supplied through the fuel pole 51 to the ion-exchange film 29. Also, Oxygen (O2) is supplied through the air pole 52 to the ion-exchange film 29.
In the fuel cell, hydrogen and oxygen undergo the following chemical reaction:2H2+O2→2H2O+electric energy+heatThis is a chemical reaction that is invert to the electrolysis of water. The reaction yields electric energy. The heat generated along with the electric energy can be absorbed by an appropriate cooling method in which the cooling water is circulated.
The ion-exchange film 29 used in the fuel cell has been made by synthesizing straight chains 54 and side chains 56. The straight chains 54 are spaced from one another at interval d0. The side chains 56 branch from the straight chains 54. In Nafion (registered trademark of E.I. du Pont de Nemours and Co.) known widely as an ion-exchange film, the straight chains 54 and the side chains 56 have such molecular structures as specified in FIG. 10.
In these molecular structures, the straight chains 54 are Teflon (registered trademark) groups and the side chains 56 are those formed by combining functional groups. Some of the functional groups shown in FIG. 10 may be removed or substituted by other functional groups, or other functional groups may be added, to alter the molecular structure of the ion-exchange film. The performance of the ion-exchange film can thereby be changed in various ways.
Having this specific molecular structure, the ion-exchange film 29 allows the passage of protons H+ and does not allow the passage of electrons e− and gas, as illustrated in FIG. 9B. Namely, the film 29 performs ion exchange. The higher the ion-exchanging performance, the higher the performance of the fuel cell. The ion-exchanging performance is considered to change in accordance with the molecular structure shown in FIG. 9C. Specifically, it is influenced by the interval d0 between the straight chains, the arrangement of the side chains 56, and the like.
Hence, it is recommended that the molecular structure of ion-exchange film or the like, which is made of macromolecular organic material, be determined in order to evaluate performance of the macromolecular organic material. Methods of determining the molecular structures of macromolecular organic materials are known. Among these methods are the NMR-measuring method and the IR-measuring method. In the NMR method, an NMR (Nuclear Magnetic Resonance) spectrometer is employed. In the IR method, an IR (Infrared) spectrophotometer is used.
The NMR-measuring method utilizes the phenomenon called “nuclear magnetic resonance,” in which the amplitude of magnetic moment changes when an electromagnetic wave is applied to an atom whose nuclear has magnetic moment, in order to determine the molecular structure, etc. of a sample. The IR-measuring method determines the molecular structure, etc. of a sample, from the infrared absorption spectrum, i.e., the relation between the intensity of the infrared beam passing the sample (plotted on the ordinate) and the wavelength of the infrared beam (plotted on the abscissa).
With the NMR-measuring method and the IR-measuring method, however, it is difficult to obtain reliable evaluation of the sample, by using a measuring apparatus of simple configuration. Further, they cannot determine the molecular structure of macromolecular organic materials such as ion-exchange film, while maintaining the materials at such high humidity and such high temperature as they are set when they are used in practice. This is why macromolecular organic materials, such as ion-exchange film, are not evaluated by means of in-situ measuring at present. In other words, the materials are not evaluated for their molecular structures in the very conditions they are used.